目的
BottomSheetDialogFragmentで全画面表示だけ有効にしたい
コード
override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {

    val dialog = super.onCreateDialog(savedInstanceState) as BottomSheetDialog

    dialog.setOnShowListener { dialog ->
        val d = dialog as BottomSheetDialog

        val bottomSheet = d.findViewById(com.google.android.material.R.id.design_bottom_sheet) as FrameLayout?
        val behavior = BottomSheetBehavior.from(bottomSheet)
        behavior.state = BottomSheetBehavior.STATE_COLLAPSED

        behavior.setBottomSheetCallback(object : BottomSheetBehavior.BottomSheetCallback() {
            override fun onSlide(bottomSheet: View, slideOffset: Float) {
                //何もしない
            }

            override fun onStateChanged(bottomSheet: View, newState: Int) {
                //この条件分岐追加しないと画面が消えた後モーダルの半透明黒マスクだけが残る
                if (newState == BottomSheetBehavior.STATE_HIDDEN) {
                    dismiss()
                    behavior.state = BottomSheetBehavior.STATE_COLLAPSED
                }
                //途中で止まろうとするので強制的に全画面表示する
                else if (newState == BottomSheetBehavior.STATE_COLLAPSED) {
                    behavior.state = BottomSheetBehavior.STATE_EXPANDED
                }
            }
        })

        //下から出てきて全画面表示されるようにする
        behavior.state = BottomSheetBehavior.STATE_EXPANDED
    }